The study presents the results of a research on the frequency of infection with Enterobius vermicularis in different urban and rural human populations, conducted by Zoology Department of Podlaska Academy in Siedlce between 1998 and 2006. Since 2001, samples from one examinee were collected seven times. On the basis of the seven tests, a table of the frequency of infection and the efficiency of its detection was presented. The study indicates the populations in which all the infected were detected earlier than after the seventh test. It also presents the results of family infection examination (there were two groups of the examined: A--only children, B--children as well as parents): out of 125 families 47 (37.6%) were infected. The author concluded that the method of taking pinworm samples should be standardized to the Graham method with the samples collected on seven consecutive days, and that whole families should be examined wherever one person is detected to be infected.